HAL Mines Nantes

    Measurements of low-p$_{T}$ electrons from semileptonic heavy-flavour hadron decays at mid-rapidity in pp and Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV

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    International audienceTransverse-momentum (p$_{T}$) differential yields of electrons from semileptonic heavy-flavour hadron decays have been measured in the most central (0–10%) and in semi-central (20–40%) Pb–Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV. The corresponding production cross section in pp collisions has been measured at the same energy with substantially reduced systematic uncertainties with respect to previously published results. The modification of the yield in Pb–Pb collisions with respect to the expectation from an incoherent superposition of nucleon-nucleon collisions is quantified at mid-rapidity (|y| < 0.8) in the p$_{T}$ interval 0.5–3 GeV/c via the nuclear modification factor, R$_{AA}$. This paper extends the p$_{T}$ reach of the R$_{AA}$ measurement towards significantly lower values with respect to a previous publication. In Pb–Pb collisions the p$_{T}$-differential measurements of yields at low p$_{T}$ are essential to investigate the scaling of heavy-flavour production with the number of binary nucleon-nucleon collisions. Heavy-quark hadronization, a collective expansion and even initial-state effects, such as the nuclear modification of the Parton Distribution Function, are also expected to have a significant effect on the measured distribution

    Prospects of additive manufacturing for accelerators

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    International audienceAdditive manufacturing allows the production of mechanical components often much faster than traditional manufacturing. Several accelerators components built using additive manufacturing have already been qualified for use in accelerator. A workshop was held in Orsay in December 2018 to discuss the prospects of using additive manufacturing for particle accelerators and particle detectors. We report here on the prospects as far as accelerators are concerned

    New excitation functions measurement of nuclear reactions induced by deuteron beams on yttrium with particular reference to the production of $^{89}$Zr

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    International audienceWe investigated 89 Zr production induced by deuteron beams on yttrium targets at energies up to Ed = 32 MeV using the stacked-foil activation technique. Cross sections of the following nuclear reactions 89 Y(d,2n) 89 Zr, 89 Y(d,3n) 88 Zr and 89 Y(d,x) 88 Y have also been measured. Based on the measured values, we determined the thick target yields for 89 Zr and 88 Zr which is the main contaminant associated to the production of 89 Zr

    Alteration of 29Si-doped SON68 borosilicate nuclear waste glass in the presence of near field materials

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    International audienceThe leaching of 29Si-doped SON68 French nuclear waste glass was investigated in Callovo-Oxfordian (COx) water in the presence of P235GH stainless steel and COx argillite. Experiments were carried out to understand the effect of near-field materials on the rate of glass dissolution and the migration of 29Si in the claystone core. Tests were performed by using percolation cells containing glass and stainless steel sandwiched between two clay cores in two different combinations: glass/clay at 50 and 90 °C, and glass/steel/clay/at 90 °C. COx water was injected through the percolation cells at 120 bars (solution flow rate 0.05–0.38 mL d−1). Results showed that the presence of steel did not enhance the dissolution rate of the glass despite the retention of 29Si released from the glass on the corrosion products. The glass dissolution rate up to 17 months tends towards 10−4 and 10−3 g m−2 d−1 at 50 and 90 °C, respectively. The glass alteration in the presence of clay leads to the formation of calcite and Mg-silicates at 50 °C in addition to apatite and powellite at 90 °C. The main steel corrosion products were siderite, magnetite, ferrosilicates, pyrite, pyrrhotite, troilite and mackinawite. MgSO4 and CaSO4 were also identified in the presence of steel

    Production of (anti-)$^3$He and (anti-)$^3$H in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV

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    International audienceThe transverse momentum (pT) differential yields of (anti-)He3 and (anti-)H3 measured in p-Pb collisions at sNN = 5.02 TeV with ALICE at the Large Hadron Collider (LHC) are presented. The ratios of the pT-integrated yields of (anti-)He3 and (anti-)H3 to the proton yields are reported, as well as the pT dependence of the coalescence parameters B3 for (anti-)He3 and (anti-)H3. For (anti-)He3, the results obtained in four classes of the mean charged-particle multiplicity density are also discussed. These results are compared to predictions from a canonical statistical hadronization model and coalescence approaches. An upper limit on the total yield of 4He¯ is determined

    XEMIS2: A liquid xenon Compton camera to image small animals

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    International audienceAn innovative Xenon Medical Imaging System, XEMIS2, designed for small animal 3γ preclinical imaging, has been constructed, and it is currently under test and qualification at the SUBATECH laboratory. It consists of a Compton camera, containing nearly 200 kg of liquid xenon, whose main goals are the precise three-dimensional localization of the 44Sc radioactive emitter used to image the small animal and the reduction of the administered radiopharmaceutical activity in cancer diagnosis. The active volume of the XEMIS2 camera is surrounded by a set of PhotoMultiplier Tubes (PMTs) to measure scintillation light. The read-out anodes are segmented in 20000 pixels to measure ionization charges. In order to reduce the electronics dead-time during continuous data taking, a novel DAQ system specifically designed for XEMIS2 has been realized and recently tested. It consists of two independent synchronized scintillation and ionization signal detection chains. The self-triggered scintillation light detection chain has been recently tested and calibrated in XEMIS1, whose experimental results showed a good performance. XEMIS2 will be soon installed at the Center for Applied Multimodal Imaging (CIMA) in the Nantes University Hospital for further preclinical studies. To safely manage a large amount of xenon in a hospital center, a recovery and storage cryogenic subsystem called ReStoX has been conceived, successfully commissioned, and already installed at CIMA

    Faisceautisation de Lawvere-Tierney en théorie des types homotopiques

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    The main goal of this thesis is to define an extension of Gödel not-not translation to all truncated types, in the setting of homotopy type theory. This goal will use some existing theories, like Lawvere-Tierney sheaves theory in toposes, we will adapt in the setting of homotopy type theory. In particular, we will define a Lawvere-Tierney sheafification functor, which is the main theorem presented in this thesis.To define it, we will need some concepts, either already defined in type theory, either not existing yet. In particular, we will define a theory of colimits over graphs as well as their truncated version, and the notion of truncated modalities, based on the existing definition of modalities.Almost all the result presented in this thesis are formalized with the proof assistant Coq together with the library [HoTT/Coq]Le but principal de cette thèse est de définir une extension de la traduction de double-négation de Gödel à tous les types tronqués, dans le contexte de la théorie des types homotopique. Ce but utilisera des théories déjà existantes, comme la théorie des faisceaux de Lawvere-Tierney, quenous adapterons à la théorie des types homotopiques. En particulier, on définira le fonction de faisceautisation de Lawvere-Tierney, qui est le principal théorème présenté dans cette thèse.Pour le définir, nous aurons besoin de concepts soit déjà définis en théorie des types, soit non existants pour l’instant. En particulier, on définira une théorie des colimits sur des graphes, ainsi que leur version tronquée, et une notion de modalités tronquées basée sur la définition existante de modalité.Presque tous les résultats présentés dans cette thèse sont formalisée avec l’assistant de preuve Coq, muni de la librairie [HoTT/Coq
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